Long cycling trip in Japan. When?

Hey Everyone
I am planning a long cycling trip in Japan (about 2 months long, 3-4000km) but it is hard to decide which part of the year should I go.
The real question is that how bad is the rainy season? If I go before April maybe a bit cold and there is the golden weak as well, after tsuyu the temperature goes up and I would drown in my own sweat.
I do not mind some rain but since my trip would take me to the mountains many times it would be very unpleasant cycling in the rain all the time.
Any advice?
Thanks.

Have you read the reports of other travelers? (Including Japanese domestic riders one)
Japan is long fr north(Hokkaido) to south(Okinawa), there are regional differences in temperature and humidity.
It is thought that Japan is a very small island country bc it is located in the east end in the world map,
(the one of Asia's absence in the West)
but in fact it is Not.(Do you know this web?)
http://thetruesize.com/

Basic climate of regions is explained by JMA,wiki and more.
http://www.data.jma.go.jp/gmd/cpd/longfcst/en/tourist.html
http://www.data.jma.go.jp/gmd/cpd/longfcst/en/tourist_japan.html
https://en.wikipedia.org/wiki/Geography_of_Japan#Climate
If you want to run even in the rainy season,
it is better to go up fr warmer south to north before rainy season
and goal at Hokkaido during the rainy season also CTS out easier.

There are about 10 regions in Japan from Hokkaido to Okinawa Prefecture,
but in here will explain them in 4 of part.
http://wikitravel.org/en/Japan

Hokkaido :
Fr early summer to early autumn, No rainy season and lower humidity very comfort.
Although there are more nature than other areas,
it can be said that it is easy to become somewhat monotonous scenery.
Hokkaido is really really wide, see the map :)

Main land(Honshu) :
Spring till the rainy season and fall. Higher mountains area in summer also good.
Japanese riders will also concentrate on summer due to calendar relationship.

Shikoku, Kyushu and Okinawa :
Mild and no snowfall, you can run in winter. (except for some areas)
But it is easy to become a passage of typhoon fr the early summer to fall,
if you hit directly, 3 days will be stuck, and summer is pretty hot
so do not recommend if no experiences hot and humid countries than Japan.

This Japanese rider has just traversed about 3000km in 25 days total fr north to south in 1990.
but he has not dropped in many areas such as famous big city Tokyo.
http://www.geocities.jp/flyfishing_lover/travel-index.html
(He living in Tokyo)

This is mid 60ty rider challenged longer about 5500km in 47 days total.
http://yasudafamily.sakura.ne.jp/hitori/judan.html
This is rickshaw challenged about 6000km. (red lines : ferry)
https://cdn.camp-fire.jp/jbimages/68f7a07a-b70f-41d4-b27f-4cf749bb9369...

The distance can be examined by Google map, but can not calculate by bicycle.
Please search by foot or car(as excluding toll road).
Depending on type of bicycle and height difference, it would be safer to keep it around 100km/day.
Be careful as bicycle shops will be few if you leave the urban area.
The risk of punk is lower than any country, but it may still be experienced once in a long distance ride.

If you take a train with bicycle, you need a carry bag, except for some regional railways.
http://blog.worldcycle.co.jp/20140623/11129/
Basically there are no cycle racks that are common in Europe.

2 months is a long time. What I would probably do is plan for 6 weeks(to be honest I wouldn't go for more than 4 weeks) leaving just before Golden Week. The mornings in March can be very cold but the days normally warm up very quickly. I would start in Kyushu & work my way towards Tokyo. I was in Kyushu this spring from March 23rd to April 13th & was in shorts, arm & legwarmers most of the time. Some days I also wore a Gillet.

Hi there, I bike a lot here in Japan and in general I would say March, April, May, June would be best. Japan is a very humid country so if you plan on riding a lot in the rain I would worry about your bike rusting.

@guest. Spring is magnificent but I have also found some great riding in Oct/Nov. @Tamaste. What sort of riding are you planning on doing? Basing yourself in a city & riding out or touring? How are you going to get your kit to Japan?

Late February, March, and April are OK for much of Kyushu, Shikoku, and southern Honshu, but it can start getting hot in these areas in May and June. The tsuyu for June is potluck, it could rain every day or have no rain at all, but in most years, there are at least a couple of weeks with steady rains. When it does rain, it's slightly cooler but the humidity is high whether it rains or doesn't. The same months in Tohoku and Hokkaido still have snow on the ground, especially in the mountains, but by June it has warmed up and isn't as rainy or hot as southern Japan. Snow is still piled high around Hakkoda-san in Aomori at the end of May although the roads are clear.

For the fall season, it can be nice up north, but it can be hot and humid well into October and November in the southern areas, especially if you get close to the Kuroshio Current (Nagasaki, Kagoshima, Kochi). By the end of November, these southern areas start to cool off. The main drawback in the fall (October and November) are the occasional typhoons that blow through. These can affect the entire country depending on their path. I was delayed once driving to Hokkaido by an Aomori-Hakodate car ferry cancellation and had to backtrack down to Hirosaki to find a hotel room.

No matter when you go, you're going to get some rain; it's Japan and all those rice fields need lots of water. Personally, I would avoid June, July, & August in the south as it's just too humid.

Thanks everyone, these informations help me a lot.
Stan, I will do touring with panniers and tent as my accommodation. As it stands now I will fly to Fukuoka (Maybe Hiroshima...) and go up North. I admit that a month long trip easier to organise and cheaper as well but I might never gona make it again to Japan so I would like to see as much as possible.

I definitely agree with Oct/Nov, because it's supposed to be the mildest time of the year in Japan.

For this reason, the 1964 Tokyo Olympics was held on October 10, which was the date with least rainfall recorded in Japan (but later Olympics are all held in August, I believe, for broadcasting reasons!). The "shuugaku ryoko" which is one of the longest trips that schools organize for their students are generally held during October and November because of the climate. School trips for Okinawa (one of the typical destinations for schools) are even held during those months, because the climate is a lot milder than mid-summer and yet you can still swim.

In other words, you need to watch out for large school trip crowds during those months, but since it's not vacation time, there will be less crowd compared to the big holidays.

I don't even want to know how much it's going to cost you to get your bike & camping gear to Japan. I stay at hotels & do day rides. If I choose the airline carefully the bike doesn't cost anything extra. Generally you have to be careful with your routes as a lot of Japan is built up & not huge fun to ride so planning & Google streetview is essential. If you don't mind about being off the beaten track how about this for an idea. Fukuoka to Beppu. Ferry to Yawatahama. Ride to Onomichi including the Shimanami kaido then to the Kibi plain and on from there. Or you could tour Shikoku itself. http://www.asahi.com/ajw/articles/AJ201705210001.html

Hopefully it will not be much to get my gear to japan. Most of the airlines allow 2 baggage for free and one of them can be bicycle I think.
That Fukuoka-Beppu trip sounds nice but since I am as poor as a church mouse (let's say...) can't really get the luxury to fly from Europe to Japan for a short trip. The camping is cheap and I like it.

I meant the whole thing as part of a longer trip. That would get you from Fukuoka to Okayama & then you could head for Kyoto & up round Lake Biwa to Kanazawa, then on. . .. Make sure you are absolutely sure about the luggage rules. I flew Japan Airlines, Heathrow to Fukuoka and yes you got two bits of baggage one of which could be the bike but it had to fit the normal luggage rules. That is to be under 23kg and height+length+width had to be less than 203cm. The first was easy, the second was a close run thing and that was for a bike without guards or a rack & no camping kit.

I still have a year to work it out. I might fly with Brittish Airways, their policy is quite good.
Maybe I will go in September-October and start with Hokkaido and go South.
At the moment I am looking for a good second hand bike because my current bike does not suitable for this tour. It's been a few years now since my last longer trip.

I have flown BA with the bike and it worked well. They have the most relaxed luggage rules for bikes that I have found now that Virgin no longer fly from the UK to Tokyo. I flew JAL because they were 300 pounds cheaper and I could pack the bike to their dimensions(just). Think about the transfer at Tokyo if you are going to fly to Fukuoka. I barely made it and needed all the help that the airline staff could provide to do so. I am sure you have already looked but there are threads on this forum about camping in Japan that are worth reading.